We evaluated the late clinical status of 34 patients undergoing operation for discrete subaortic stenosis. Followup ranged from 1 to 245 years with a mean of 13.7 years; 3 of the 34 patients could not be located at the time of this evaluation. The average age at the time of operation was 16.8 years of age (range 5 to 55). There were 4 operative deaths (10.5%) during our early experience. The average preoperative peak systolic gradient was 98.5 mm Hg. Postoperative catheterization was performed in all patients from 2 to 168 months following operation. Postoperative gradients ranged from 0 to 200 mm Hg (mean 35 mm Hg). Seven patients had postoperative gradients greater than 50 mm Hg, ranging from 58 to 200 (mean 103 mm Hg); 5 of these 7 patients had the tunnel variety of subaortic stenosis at the time of operation. Five of the 31 patients available for late clinical evaluation died (13.8%); four of these deaths were sudden. Nineteen patients had aortic regurgitation preoperatively (61.3%); aortic regurgitation was present in 21 patients (67.7%) examined within 6 months after operation. Actuarial survival at 10 years is 87%, and at 27 years is 81%. We conclude that the resection of the subaortic membrane in this disease effectively removes left ventricular outflow tract obstruction. However, because of the striking association of aortic regurgitation and this disease, patients should continue to be followed on a long-term basis.